WO2000061947A1

WO2000061947A1 - Dual path hydraulic pump

Info

Publication number: WO2000061947A1
Application number: PCT/US2000/009772
Authority: WO
Inventors: Glenn M. Grube
Original assignee: Grube Glenn M
Priority date: 1999-04-13
Filing date: 2000-04-12
Publication date: 2000-10-19
Also published as: WO2000061947A9; AU4234600A

Abstract

A hydrostatic gear pump having a rotatable ring gear (50), a central sun gear (40), and plural planetary gears (44, 46, 48) engageable between the ring gear (50) and the sun gear (40). A two-part housing (80, 84) provides inlet fluid channels (68, 72) to the planet gears (44, 46, 48) and outlet fluid channels (58, 60) from the planet gears (44, 46, 48) so that each planet gear provides dual fluid transfer paths. Each planet gear fluid inlet (58, 60) is arranged oppositely, and each planet gear fluid outlet (58, 60) is arranged oppositely to thereby provide balanced forces on each planet gear (44, 46, 48) and reduce bearing wear.

Description

DUAL PATH HYDRAULIC PUMP

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to gear-type pumps, and more particularly to high capacity hydraulic pumps having plural transfer paths internal to the pump.

BACKGROUND OF THE INVENTION

Hydraulic pumps have long been known for transferring a fluid from one location to another location. Hydrodynamic (non-positive displacement) pumps and hydrostatic (positive displacement) pumps are two general classes of machines that convert mechanical energy into hydraulic energy. Both classes of machines can also be applied in reverse as motors to convert hydraulic energy to useful mechanical energy as well. Hydrodynamic pumps/motors of non- positive type include the centrifugal and turbine designs which are generally not complicated, and are efficient for transferring fluids under low pressure. The hydrostatic type of pump/motor with its positive inlet to outlet seal design provision provides a given amount of fluid for every pump element stroke, revolution or cycle. The volumetric output from hydrostatic pumps/motors is generally independent of the system outlet resistance which is encountered (pressure demanded), thereby making such designs of pumps/motors ideal for the transmission of hydraulic energy via their fluid operating media. The rating of such pumps/motors is generally expressed as a given output in gallons per minute (GPM) at a given drive speed, or alternately rated in cubic inches or cubic centimeters of output displacement per input revolution.

Many types of hydrostatic hydraulic pumps and motors are of the spur gear element type, providing a positive, though fixed displacement output in relationship to input drive speed. A pair of spur gears situated to provide tooth enmeshment will alternately create inlet and outlet zones as their teeth advance toward and retreat from an enmeshed condition. Once the fluid has filled the void generated by the retreat action, it is transferred in pumping chambers formed between the gear teeth passing in close proximity to a pump housing. The clearance between the tips of the gear teeth and the housing is often an interference fit. In a conventionally designed two-gear hydraulic pump/motor design, one gear is connected to a drive shaft providing an input/output interface for the pump/motor, and such gear meshes with another gear. The gears thus rotate in opposite directions and carry fluid from a common inlet in different directions, via the pumping chambers, to a common outlet. In this design format, the gears carry the fluid more than halfway around for each revolution in transferring the hydraulic fluid from the inlet to the outlet. Side plates, or wear plates, generally engage opposing sides of the gears to minimize leakage of the fluid from the pressurized outlet back to the inlet. In the conventional two-gear type of hydrostatic pumps/motors noted above, each gear is subjected to a low-pressure inlet and a high-pressure outlet that are diametrically opposed to one another. At high outlet pressures, a substantial radial force is imparted to the gears, and thus to the gear shafts and bearings supporting them. Due to their inherently unbalanced loading characteristics, such designs require the use of heavy duty bearings and gear shafts to maximize unit life potential. In addition to decreasing the life of the pump/motor units, the shaft deflection also tends to compromise the unit's volumetric efficiency as its side plates adjust to the tipping motion of the gear faces allowing leakage rate increases from the unit's high to low pressure port. In U.S. Pat. No. 3,397,645 by Mosbacher, et al., a four-gear hydrostatic pump is disclosed. According to the description of the Mosbacher patent, a radially balanced pressure is achieved around the gear case. This is achieved by providing a first inlet where two gears come out of mesh, and a second, diametrically located inlet is provided where two gears come into mesh, and a second diametrically located discharge outlet is provided where yet two other gears come into mesh. With this arrangement, there is a balanced pressure with regard to the gear case, in that pairs of inlets and outlets are oppositely located within the gear case. However, as to each spur gear, there is a high pressure discharge outlet located on the opposite side of a low pressure inlet. Hence, each gear itself is subjected to an overall radial force, thereby causing increased wear on the bearings as a function of the unit's pressure differential. In the Mosbacher design, even though four spur gears are utilized, each gear is associated with a single fluid delivery path.

From the foregoing, it can be seen that a need exists for an improved, hydrostatic pump/motor design that provides a dual transfer path with respect to specific gear elements such that radial force balancing is achieved with respect to each system displacement gear. A further need exists for a hydraulic pump where the fluid requires less travel distance around its displacement gear from its inlet to its respective outlet, thereby improving the pump/motor unit's overall efficiency. Yet another need exists for a high capacity pump where each of its displacement gears provides a displacement value that is double that of comparable gear sets as used in conventional gear pump/motor unit designs. SUMMARY OF THE INVENTION

In accordance with the principles and concepts of the invention, there is disclosed a spur gear type hydrostatic pump/motor that overcomes and reduces the shortcomings and disadvantages of the prior art pumps. In accordance with a preferred embodiment of the invention, each spur gear to be force balanced engages with at least two other gears to thereby provide dual fluid transfer paths. Both inlets as to each gear, and both outlets are oppositely located so as to provide a force balanced radial force to the gears.

In one embodiment of the invention, the pump/motor includes a rotatable ring gear with internal teeth, and a central sun gear and the ring gear are plural planet gears. The set of gears constitute a gear assembly. When two planet gears are employed, each such planet gear is associated with two fluid inlets and two high pressure outlets, thereby providing a force balanced planet (displacement) gear. The sun gear in such a unit would include two equidistantly spaced inlets and two high pressure outlets, again providing a force balanced situation.

The ring gear, sun and planet gears are situated within a front and rear housing, one of which has an internal side face that defines a seal plate. This portion of the housing also includes a matching plurality of seal bridges that extend into the pumping gear assembly area to provide seal surfaces for the rotating teeth of gears. On the other side of the pumping gear assembly there exists a seal plate and the other portion of the housing. When the housings are bolted together, a sealed unit is formed with a pump inlet associated with one housing and a pump outlet associated with either the aforementioned inlet housing section or with its mating housing section. Each housing section is formed by various manufacturing methods to provide inlet/outlet flow channels. For example, from a single external pump inlet, the fluid is coupled to a plurality of internal gear inlets, and in like manner, the mating housing may be fabricated to provide a plurality of internal gear outlets coupled to a single external pump outlet.

In a second embodiment of the invention, the unit is arranged as noted above, with the exception that its rotatable ring gear is used as the unit's mechanical input/output interface while its sun gear idles. In a third embodiment of the invention, the unit may be arranged in either of the above noted configurations with the exception that its plurality of planet (displacement) gears may be independently or collectively employed. In a fourth embodiment of the invention, the unit may be arranged in any of the three previous configurations with sun gears of varying diametrical pitch ratio to the unit's planet gears providing potential input/output speed increasing or decreasing capability.

In a fifth embodiment of the invention, the unit may be arranged in any of the four previous configurations with additional planet gears. Increasing unit displacement values considerably and potentially providing the greatest unit power density and application flexibility currently available in the general power transmission component market.

In a sixth embodiment of the invention, the unit may be arranged in any of the five previous configurations. Unlike those examples, however, these devices are intended for use in low power demand systems and can be constructed with lower cost, lower mass, lower strength components manufactured from alternate materials, i.e. aluminum alloys and plastics, utilizing manufacturing processes including, but not limited to, molding, continuous casting or extrusion methods.

In a seventh embodiment of the invention, the unit may be arranged in any of the six previous configurations, but lacking any mechanical input/output interface. More specifically, an intended use is the amplification of an independently supplied hydraulic power transmission source providing increased fluid flow rate output and/or increased system output pressure potential, as required. (Note, this embodiment, with linearly displaced auxiliary piston pump option will also provide increased operator safety via the elimination of extreme high pressure flexible fluid conductors.)

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages will become apparent from the following and more particular description of the preferred and other embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters generally refer to the same components or elements throughout the views, and in which:

Fig. 1 diagrammatically illustrates a three-gear hydraulic pump and the dual liquid transfer path provided by the central sun gear;

Fig. 2 illustrates a simplified five-gear hydraulic pump gear assembly utilizing a ring gear, a sun gear and plural planet gears, where each planet gear provides dual path liquid transfer paths;

Fig. 3 is a cross-sectional view of the five-gear hydraulic pump gear assembly contained within a housing that includes seal bridges between the gears for defining gear chambers for transferring liquid via dual transfer paths;

Fig. 4 is an enlarged cross-sectional view of a portion of Fig. 3; Fig. 5 is a partial cross-sectional view of the hydraulic pump of Fig. 3, showing the left and right housing halves with the respective liquid inlets and outlets formed therein;

Figs. 6 and 7 diagrammatically show other embodiments of the invention having different sets of gears; and

Figs. 8 and 9 diagrammatically show other embodiments of the invention that utilize concentric ring gears with planet gears therebetween.

DETAILED DESCRIPTION OF THE INVENTION

The various embodiments of the invention are described in detail below, and shown in the different drawings. While the preferred form of the invention is shown and described in connection with apparatus that provides a hydraulic pumping function, those skilled in the art will readily appreciate that such apparatus can be readily adapted for use as hydraulic motors. In addition, while the various embodiments employ spur-type gears to achieve the pressurization and transfer of liquid, the utilization of such type of gear is not essential to the practice of the principles and concepts of the invention. In the description that ensues, it will be noted that each embodiment employs at least one spur gear arranged in a pump housing with other apparatus, so that there are at least two hydraulic inlets and two hydraulic outlets associated with such gear. Moreover, and in accordance with an important feature of the invention, each of the low pressure inlets are arranged at diametric locations with respect to the spur gear, and each of the high pressure outlets are also arranged at diametric positions with such gear. In this manner, dual flow paths of liquid are provided, and the spur gear is not subjected to unequal radial forces. This substantially prolongs the useful life of the pump, in that gear bearing wear is reduced. By providing dual flow paths per gear, the pumping volume is substantially increased.

With reference now to Fig. 1, there is illustrated a dual flow path hydraulic pump according to one embodiment of the invention. Shown is a pump configuration 10 having a center spur gear 12 that is preferably driven by an external power source. The center gear 12 has peripheral gear teeth 14 that mesh with a first driven gear 16 and a second driven gear 18. In the illustration of Fig. 1, the center gear 12 turns in a counterclockwise direction, as shown by arrow 20. As the center gear 12 rotates in a counterclockwise direction, the first and second driven gears 16 and 18 rotate in clockwise directions, also as shown by respective arrows. Each spur gear 12, 16 and 18 rotates with respect to shafts that are journaled within a housing 22. Machined or otherwise formed in the housing 22 are recessed areas for receiving therein the respective spur gears. Recessed area 24 has an annular sidewall partially around the center gear 12. The teeth 14 of the center gear 12 are clearanced from the sidewall of the recess 24 so as to substantially form a liquid seal therebetween while the gear is rotating. The driven gears 16 and 18 rotate within respective recessed areas 26 and 28 in a similar manner. The tooth profile of each spur gear 12, 16 and 18 are of conventional design for providing pockets for carrying the liquid during rotation of the respective gears. It is contemplated that the profile of the gear teeth will include a design pressure angle adapted to provide the necessary sweep. Formed in the housing 22 is a first liquid inlet 30 and a second liquid inlet 32. Also formed in the housing 22 is a first liquid outlet 34 and a second liquid outlet 36. The liquid inlets 30 and 32 open within the housing 22 into chambers formed by the respective recessed portions of the housing and the meshed gears. Liquid inlet 30 opens into a chamber that is sealed by the teeth of the center gear 12 and the driven gear 16 and respective curved sidewalls of the housing recessed areas. While not shown, side pressure plates can be utilized to provide a liquid seal along the side faces of the gears. The liquid inlet 32 opens into a chamber that is also sealed by the teeth of gears 12 and 18 that rotate very closely to the curved sidewalls of the respective housing recessed areas. The liquid outlets 34 and 36 also open into respective chambers that are sealed by the gear teeth and the curved sidewalls of the recessed housings. It can be seen that with the possible exception of small liquid leakage around the gears, liquid is transferred from the inlet 30 via the small pockets between the meshed gears 12 and 16 to the liquid outlet 34. In like manner, liquid exiting the inlet 32 into the chamber is transferred via the meshed gear teeth 12 and 18 to the liquid outlet 36.

An important feature is to be noted from the hydraulic pump illustrated in Fig. 1. Each liquid inlet 30 and 32 is located at diametric positions with regard to the center gear 12. Similarly, the high pressure liquid outlets 34 and 36 are also located at the diametric positions with regard to the center gear 12. With such an arrangement, the loading forces on the center gear 12 are balanced, whereby bearing wear is substantially reduced. Force balancing with regard to the driven gears 16 and 18 is not achieved in this embodiment, but is achieved in other embodiments to be described below. With the provision of dual pumping paths, the pump 10 can transfer twice the volume of liquid as compared to conventional pumps with comparable size gears and teeth.

While Fig. 1 is illustrative of the principles and concepts of the invention, it should be noted that the pump 10 would necessarily include pressure plates on each side of the gear to again reduce the leakage of the liquid from the high pressure outlets to the lower pressure liquid inlets. Preferably, each liquid inlet 30 and 32 would be channeled in the housing to a common pump inlet (not shown). Similarly, the high pressure liquid outlets 34 and 36 would be channeled in another portion of the housing to a common liquid pump outlet. Two halves of the housing 22 would be bolted together to simplify the assembly and/or repair of the pump 10. Figs. 2-4 illustrate another embodiment of the dual path hydraulic pump constructed according to another embodiment of the invention. In particular, Fig. 2 illustrates diagrammatically the various gears involved, together with the low pressure liquid inlet ports and the high pressure liquid outlet ports. Fig. 3 is a cross-sectional view of such embodiment, showing the seal bridges that provide distinct liquid inlet and outlet chambers with respect to each of the spur gears, including the ring gear. Fig. 4 is a cross- sectional view showing the housing portions and the liquid inlet channels and liquid outlet channels formed therein. All embodiments illustrated and described that include the ring gear, as shown in Fig. 2, may also be arranged to alternately employ mechanical Input/Output interface at the sun or planetary gear shafting or at the outside diameter of the ring gear via a geared or friction drive surface provision.

With reference to Fig. 2, there is shown a central sun gear 40 rotatable with regard to a shaft 42. The shaft 42 can be driven by an external source. The central gear 40, otherwise known as a "sun" gear, drives three planetary spur gears identified by reference numerals 44, 46 and 48. The planetary gears 44-48 are rotatable on respective shafts that are journaled within sleeve bearings press fit within the housing portions. Each spur gear is either machined integral with the respective shaft, or keyed thereto by an appropriate key and slot arrangement. A ring gear 50 includes teeth 52 that mesh with each of the planetary gears 44-48. The rotation of the planetary gears 44-48 causes a corresponding rotation of the ring gear 50. An arrow indicating the direction of rotation is shown with respect to each spur gear shaft, as well as the ring gear 50. Those skilled in the art can readily appreciate that the teeth of the gears are formed with a shape so that small pockets are formed therebetween so as to carry a liquid therein during gear rotation.

In accordance with an important feature of the invention, there is illustrated by way of cross hatching, the low pressure liquid inlet ports associated with each gear. The high pressure liquid outlet ports are shown by solid circles. Each planetary gear of this embodiment is associated with two diametrically-located inlet ports and two diametrically-located liquid outlet ports. With reference to the sun gear 40 and the planetary gear 44, there is provided in one housing portion a first liquid inlet 54 and a second liquid inlet 56. In addition, there is provided on the other housing portion a first liquid outlet 58 and a second liquid outlet 60. As noted in the drawing, the liquid inlets are substantially larger than the liquid outlets, by a factor of two or more. The size of the liquid inlets are formed in relation to the size of the liquid outlets so that liquid cavitation does not occur at inlets during the pumping operation. During the pumping operation, and as will be described more fully below, liquid transferred from the first liquid inlet 54 is carried by the planetary gear 44 to the first liquid outlet 60. In like manner, liquid transferred from the second liquid inlet 56 is carried by the planetary gear 44 to the second liquid outlet 58. With regard to the sun gear 40 and the planetary gear 46, there are corresponding liquid inlets 60 and 62, as well as liquid outlets 64 and 66. Liquid inlet 60 and liquid outlet 66 function together as a first transfer path, and liquid inlet 62 and liquid outlet 64 function together as a second transfer path. With respect to the sun gear 40 and the planetary gear 48, liquid inlet 68 functions in cooperation with liquid outlet 70, and liquid inlet 72 functions in cooperation with liquid outlet 74. It should also be noted that due to the placement of the inlet and outlet ports with respect to the ring gear 50, such ring gear is also force balanced.

The operation in transferring liquid from a low pressure inlet to a high pressure outlet can be seen with reference to Fig. 3. The cross-sectional view of Fig. 3 is taken in such a manner as to show the high pressure liquid outlets formed in one half of the housing. It should be understood that the other half of the housing (not shown) has formed therein the low pressure liquid inlets. In any event, the housing portion 80 has formed therein the high pressure liquid outlets 58, 60, 64, 66, 70 and 74. The ring gear 50 rotates within an annular bearing 82 that is compression fit within an opening in the housing half 80. As noted above, the shaft of each planetary gear, as well as the sun gear, is journaled ai one end thereof within the housing 80. The other ends of the respective shafts are journaled within the other half of the housing, as shown in Fig. 5.

Formed integral with the housing half 80 are three seal bridges identified by reference numerals 86, 88 and 90. Each seal bridge, for example, seal bridge 86, is machined with four curved surfaces, each of which provides a different fluid seal with respect to the teeth of different gears. Fig. 4 shows an enlarged, partial cross-sectional view particularly illustrating seal bridge 86. Seal bridge 86 includes a first convex-shaped outer curved surface 92 that provides a clearance seal with respect to the teeth 52 of the ring gear 50. A concave sealing surface 94 of the seal bridge 86 provides a clearance seal with respect to the teeth of the spur gear 46. A similar-shaped concave surface 96 provides a clearance seal with respect to the teeth of spur gear 44. Lastly, a concave surface 98 provides a clearance seal with respect to the teeth of the sun gear 40. Preferably, the seal surfaces 92, 94, 96 and 98 are hardened, such as by a melanizing process. The other seal bridges 88 and 90 are similarly constructed to provide respective seal surfaces to the corresponding ring, sun and planetary gears.

Taking Fig. 2 in conjunction with Fig. 4, the following describes the manner in which the seal bridge 86 forms different pumping chambers that are effective to transfer liquid from a low pressure inlet to a high pressure outlet. With reference to planetary gear 46, one housing half 84 (Fig. 5) provides a low pressure liquid inlet at the location defined by reference numeral 62. The teeth of the planetary gear 64, as well as the teeth of the ring gear 50, and the seal surface 94 of the seal bridge 86 provide a chamber for the inlet of liquid thereto. As the planetary gear 46 is driven in a counterclockwise direction by the sun gear 40, the liquid from the inlet 62 is carried by the teeth of the spur gear 46 in a counterclockwise direction toward the liquid outlet 64. The liquid outlet 64 formed in the housing half 80 is in communication with another chamber formed by the teeth of the sun gear 40, the teeth of the planetary gear 46 and the seal surface 98 of the seal bridge 86. The generalized chamber is shown by reference numeral 100. It can be appreciated that the inlet and outlet chambers are not defined by stationary boundaries, but rather vary in size and shape due to the rotation of the respective gears. Other inlet and outlet chambers are formed in conjunction with the seal surface 96 of the seal bridge 86. The other seal bridges 88 and 90 form chambers for both the liquid inlets and liquid outlets of the respective gears.

Fig. 5 illustrates a cross-sectional view through two planes of the embodiment of the hydraulic pump shown in Fig. 3. This view illustrates the left half 80 of the housing and the right half 84 of the housing, with the various liquid channels formed therein. With regard to the left half 80 of the hydraulic pump housing, it is seen that high pressure liquid outlet ports 58 and 60 are formed therein. The liquid outlet ports 58 and 60 are cored or otherwise formed so as to be directed to the pump outlet 102. It is also seen from Fig. 5 that the left housing half 80 includes a large annular recess for press fitting therein of the ring gear bearing 82. The bearing 82 can be of a hydrodynamic bronze bearing, or other suitable bearing. The outside surface of the ring gear 50 rotates with respect to the bearing 82. As is convention, the liquid being pumped provides the lubricating agent for all of the bearings. As can be further seen from Fig. 5, the left half of the housing 80 is machined with a recessed area having a flat surface 104. The flat surface 104 is clearance fit with respect to the side surfaces of the ring gear 50, the sun gear 40 and the planet gears 44, 46 and 48. As such, a left side thrust plate is not needed. Rather, the housing portion 80 itself provides a side thrust plate to prevent reverse leakage of the liquid from the high pressure outlet ports back to the low pressure inlet ports. While not shown in Fig. 5, formed integral with the left half 80 of the housing are the three seal bridges 86, 88 and 90 (Fig. 3). The seal bridges extend laterally outwardly from the face 104 of the recessed area of the housing portion 80. Preferably, the seal bridges 86-90 extend orthogonal to the recessed surface 104 to the same extent as the opposite face surface of the gears, as shown by reference numeral 106. With this arrangement, all four spur gears, as well as the ring gear 50, in addition to the ends of the seal bridges 86-90 all abut against a right side thrust plate 108. The side thrust plate 108 provides a clearance fit to the side faces of the gears, as well as the seal bridges, to thereby prevent a reverse flow leakage of the liquid from the high pressure outlet ports back to the low pressure inlet ports.

The right housing half 84 is journaled to receive the bearing shafts of all the spur gears. In addition, the right housing half 84 is cored or otherwise forged to form therein all of the low pressure inlet ports, two of which are shown by reference numerals 68 and 72. These inlet ports 68 and 72 provide the inlets to the planetary gear 48. The two other pairs of inlet ports are similarly formed in the right housing half 84 so as to provide dual inlets to the other spur gears 44 and 46. Because the inlet ports corresponding to each spur gear are larger than the high pressure outlet ports, a larger-diameter pump inlet 110 is required. In this embodiment of the invention, it is contemplated that the inside diameter of the pump outlet 102 will be about two inches, whereas the inside diameter of the pump inlet 110 will be about 3.5 inches in diameter. As other alternatives, the right pump housing 84 can be formed so that the pump inlet 110 is located other than in the center of the backside thereof. This would allow the drive shaft 42 to extend through both pump housings 80 and 84 so that multiple pumps can be ganged together. In addition, the pump outlet 102 can be formed on the annular sidewall of the left pump housing 80. The pump can be constructed so as to function as a flow divider by providing multiple pump outlets. Preferably the dual outlets from the various planet gears would be directed to the same outlet to maintain a balanced force on each gear. It is also feasible to similarly provide multiple pump inlets.

The left pump housing 80 and the right pump housing 84 can be joined together and bolted with appropriate bolts 112. In order to provide a high pressure seal between the housing portions 80 and 84, an O-ring 114 and appropriate annular housing grooves can be utilized. The pump embodiment of Fig. 5 is assembled in the following manner. The ring seal 82 is first press fit into the left housing half 80. The ring gear 50 is then placed in the bearing 82. Next, the sun gear 40 and the shaft 42 are lowered into the center housing bearing. Then, all the planet gears 44, 46 and 48 are installed in the respective bearings and meshed with the sun gear 40 and the ring gear 50. The side thrust plate 108 is then lowered onto the various bearing shafts, and within the recessed area formed in the left housing half 80. Lastly, the O- ring 114 is placed in the annular groove formed in the left housing half 80. After assembly of the gear assembly in the left housing half 80, the right housing half 84 is registered with the gear bearing shafts and lowered onto the left housing half 80. The housing halves 80 and 84 are then bolted together with the bolts 112.

From the foregoing, a pump embodiment is illustrated in which each planetary gear is associated with dual flow paths. Moreover, each flow path is arranged with each spur gear so as to provide balanced forces to such spur gears. In this embodiment, each of the three planetary gears 44, 46 and 48 is characterized by two oppositely directed inlet ports and two oppositely directed outlet ports. The sun gear 40 is characterized by three inlet ports spaced therearound, and three outlet ports, also spaced therearound. Those skilled in the art can determine the exact spacing, location and arrangement of each planet gear. The provision of the ring gear 50 allows the force balanced operation of each of the spur gears. In accordance with an important feature, the seal bridges disposed between the ring gear and the various spur gears function to provide sealed chambers so as to allow multiple liquid paths associated with each gear. While the embodiment depicted in Figs. 2-5 is constructed so that the sun gear 40 is driven by an external power source, the pump can also be constructed so that the ring gear 50 is also the driven gear. As yet other alternatives, any one or more of the planet gears can be driven by an external power source.

Those skilled in the art will recognize and appreciate that the illustrations and detailed descriptions disclosed are not limited to use as hydro-mechanical power conversion devices. Absent the depicted or described mechanical Input/Output interfaces, i.e. shafts, gears, friction drive surfaces, etc., the units may also be used in applied hydraulic power transmission systems to proportionally divide its output and to selectively amplify its individual planetary output pressure generation and flow rate potentials.

Figs. 6 and 7 illustrate yet other embodiments of the invention. These embodiments are simplified and do not show the seal bridges. Fig. 6 diagrammatically illustrates a four-gear hydraulic pump 120. This embodiment includes a center sun spur gear 122 and a pair of planetary gears 124 and 126. When driven, the sun gear 122 meshes with the planetary gears 124 and 126 and thus drives such gears. Each planetary gear 124 and 126 meshes with internal teeth of a ring gear 128, whereupon the ring gear 128 rotates. In the event the sun gear 122 is driven in the direction shown by the arrow 130, then the remaining gears rotate in the directions shown by the respective arrows. In this embodiment, each gear is associated with a pair of liquid inlets shown in cross hatching, and a pair of liquid outlets, shown in solid. With this embodiment, there are a total of four liquid inlets and four liquid outlets, the total producing a high volume transfer of liquid. Moreover, the liquid inlets and the liquid outlets are oppositely directed with respect to the spur gears, thereby substantially reducing any net radial force on the gears. Fig. 7 illustrates a six-gear hydraulic pump 140. In this embodiment, there is a central sun gear 142 that meshes with four planet gears 144-150. Each planet gear meshes with internal teeth of a ring gear 152. Again, each planet gear is associated with a pair of liquid inlets and a pair of liquid outlets, each oppositely directed so as to provide a net zero radial force on the respective gear. The sun gear 142, on the other hand, is associated with four liquid inlets and four liquid outlets. Nonetheless, the liquid inlets are oppositely directed, as are the liquid outlets, thereby providing forced balancing to the sun gear 142. It can readily be seen from the foregoing that those skilled in the art may desire to construct the sun gear with a much larger diameter to thereby accommodate many more planet gears therearound. The volume of liquid pumped can thereby be increased even further. Figs. 8 and 9 illustrate yet other embodiments of the invention. Again, the seal bridges are not shown for purposes of simplicity. In the embodiment 160 of Fig. 8 there are provided concentric ring gears 162 and 164, where the center ring gear 164 has both internal and external teeth. The internal ring gear 164 can be given directly, or by way of a drive gear 166. A plurality of planet gears, one shown as reference numeral 168, are engageable between the outer teeth of the ring gear 164, and the inner teeth of the ring gear 162. As can be seen with respect to the planet gear 168, a dual path flow of liquid is provided, thereby maintaining a balanced force on each such planet gear. It is noted that the embodiment 160 of Fig. 8 is similar to that shown in Fig. 7. Essentially, the sun gear 142 of Fig. 7 has been replaced by a ring gear, which results in the embodiment of Fig. 8. With reference to Fig. 9, the pump 170 again includes an outer ring gear 172, an inner ring gear 174 having both external teeth and internal teeth, and a plurality of planet gears 176 meshed therebetween. In addition, a sun gear 178 is mounted for rotation centrally within the ring gear 174, and a second set of planet gears (one shown as reference numeral 180) are mounted for rotation between the sun gear 178 and the internal teeth of the ring gear 174. The central sun gear 178 can be driven by an external source. As can be seen with respect to the first set of planet gears 176 and the second set of planet gears 180, each such set has inlet and outlet ports that provide fluid balancing to each set of planet gears. Although this embodiment is rather complicated, it provides a high volume of liquid transfer from a pump inlet to a pump outlet.

From the foregoing, disclosed in the various embodiments are hydraulic pump configurations, each of which has at least one liquid transfer gear that provides a dual flow path of the liquid. The liquid inlets and liquid outlets associated with such gear are located opposite each other with respect to the gear so that such gear experiences a net zero radial force. By providing dual flow paths, the pump produces a substantially higher volume of pressurized liquid. When utilizing plural gears having dual flow paths, yet increased volumes of liquid can be experienced. While the present invention has been described above with a certain degree of particularity, it is understood that the present disclosure has been made by way of example, and changes in detail of structure may be made to the invention without departing from the spirit and scope thereof, as defined by the appended claims. Those skilled in the art may prefer to combine the various and different features of the embodiments disclosed, or utilize the individual features and advantages.

Claims

I CLAIM:

1. A fluid pump, comprising: a housing having at least one inlet and at least one outlet; a plurality of gears engageable together so that when one gear is driven the other gears are correspondingly driven; at least one fluid transfer gear having a pair of gear inlets and a pair of gear outlets so that when said fluid transfer gear is rotated, fluid is pumped from a respective gear inlet to a corresponding gear outlet; a fluid delivery channel system for coupling fluid from a pump inlet to each said gear inlet; and a fluid outlet system for coupling pressurized fluid from said gear outlets to a pump outlet.

2. The fluid pump of Claim 1, wherein said fluid pump includes a single pump inlet and a single pump outlet.

3. The fluid pump of Claim 1, wherein said gear inlets are arranged in diametric positions with respect to said fluid transfer gear.

4. The fluid pump of Claim 1, wherein said gear outlets are arranged in diametric positions with respect to said fluid transfer gear.

5. The fluid pump of Claim 1, further including a rotatable ring gear, and at least one of said gears mesh with said ring gear.

6. The fluid pump of Claim 5, wherein said gears transfer fluid in a dual path from a respective gear inlet to a respect gear outlet.

7. The fluid pump of Claim 5, wherein each gear is pressure balanced so that minimal radial force of said fluid is exerted on the gear.

8. The fluid pump of Claim 5, wherein said ring gear is driven to thereby drive said gears.

9. The fluid pump of Claim 5, wherein said housing includes a plurality of seal bridges for maintaining a seal between each plurality of the gears and the ring gear.

10. The fluid pump of Claim 9, wherein said seal bridge includes a plurality of curved surfaces forming a seal with each of said gears and said ring gear.

11. The fluid pump of Claim 5, where said plurality of gears includes a central sun gear not directly engageable with said ring gear, and a plurality of planet gears, each planet gear engageable with said sun gear and with said ring gear.

12. The fluid pump of Claim 1, wherein a portion of said housing defines a seal plate for sealing to face surfaces of said gears.

13. A method of pumping fluid, comprising the steps of: fixing a plurality of gears in a housing so that at least one said gear has a pair of gear inlets and a pair of gear outlets; delivering fluid from a pump inlet to each gear inlet of said plurality of gear inlets; using at least one said gear to transfer fluid from said pair of gear inlets to respective said gear outlets; and collecting pressurized fluid from each gear outlet and coupling the pressurized fluid to a pump outlet.

14. The method of Claim 13, further including balancing fluid forces on said at least one said gear so that substantially no radial fluid force is exerted thereon.

15. The method of Claim 13 , further including rotating a plurality of gears operable to transfer liquid with respect to a ring gear.

16. The method of Claim 15, further including meshing said plurality of gears with a single central gear.

17. The method of Claim 13 , further including using a plurality of seal bridges in conjunction with said gears to define inlet and outlet ports with respect to each said gear.

18. The method of Claim 17, further including using a portion of a pump housing for forming said seal bridges.

19. A fluid pump, comprising: a housing for housing components of said pump; a ring gear mounted for rotation; a plurality of planet gears mounted for rotation so that each said planet gear meshes with said ring gear; at least one sun gear mounted for rotation so as to mesh with each said planet gear; a plurality of seal bridges, each seal bridge disposed between said ring gear, at least two planet gears and said sun gear; a portion of said housing constructed so as to provide at least one pump inlet for distributing via channels a fluid to each said planet gear; and a portion of said housing constructed so as to provide at least one pump outlet for collecting via channels fluid pressurized by said planet gears.

20. The fluid pump of Claim 19, wherein said housing portions are constructed so as to provide at least two inlet ports to each planet gear and two outlet ports to each said planet gear.

21. The fluid pump of Claim 20, wherein said inlet ports and said outlet ports are arranged with respect to each said planet gear so as to provide fluid force balancing thereto such that radial forces on said planet gears are minimized.